The conventional procedure for manufacturing a conventional housing of an LED display device is shown as the follows, first injection molding to form a cover, printed an ink on a display side, then second injection molding to form a transparent member within display holes of the cover. However, it includes the step of manual disposition of the cover from one mold assembly to another mold assembly, and is relatively time-consuming and cost-ineffective. Moreover, if the second injection molding process is not successful, the defective housing is difficult to be recycled since the display side of the cover has already been printed with the ink layer.